The present invention relates to a constant-temperature liquid circulating apparatus which supplies constant-temperature liquid to a load to circulate the same.
FIG. 3 shows one example of a constant-temperature liquid circulating apparatus which has been already proposed, and a constant-temperature liquid circulating apparatus 101 comprises a refrigerating circuit section 103 for cooling constant-temperature liquid whose temperature has been elevated in a load 2, a constant-temperature liquid circuit section 104 which, after adjusting the temperature of the constant-temperature liquid which has been cooled by refrigerant of the refrigerating circuit section 103 to a predetermined temperature, supplies the adjusted constant-temperature liquid circuit section 104 to the load 2 to circulate the same, and a control section 105 which controls the temperature of the constant-temperature liquid supplied to the load 2.
The refrigerating circuit section 3 is constituted by connecting a compressor 7 which compresses proper refrigerant to produce refrigerant gas with a high temperature and a high pressure, a condenser 8 which cools and condenses the refrigerant gas to produce liquid refrigerant with a high pressure, a decompressor 9 which decompresses liquid refrigerant to temperature-reduce the same, and an evaporator 10 which evaporates the liquid refrigerant which has been pressure-reduced in the decompressor 9 in this order in series.
The constant-temperature liquid circuit section 104 comprises a tank 24 for constant-temperature liquid, a heat exchanger 25 which cools the constant-temperature liquid whose temperature has been elevated in the load 2, a heater unit 26 which has a heater 27 heating the constant-temperature liquid which has been cooled in the heat exchanger 25 up to a predetermined temperature, a pump 28 which supplies the constant-temperature liquid in the tank 24 whose temperature has been adjusted to the predetermined temperature by the heater 27 to the load 2 to circulate the same and a level switch 29 which detects a liquid level of the constant-temperature liquid in the tank 24; and all of the heat exchanger 25, the heater unit 26 and the pump 28 are assembled to the tank 24. Also, a cylindrical heater cover 30 with a bottom which surrounds the heater 27 and whose upper portion can be opened is provided around an outer periphery of the heater 27.
The control section 105 is for controlling the entire apparatus, and it comprises a temperature controller 42 which outputs a necessary signal according to a temperature signal of a temperature sensor 37, a programmable controller (hereinafter, abbreviated as PLC) 43 which outputs a necessary signal according to signals of the level switch 29 in the tank 24, a low pressure cut switch 39 and a refrigerant high pressure cut switch 20, an electromagnetic contactor/electromagnetic switch 44 which controls operations of the compressor 7 and the pump 28, current flow to the heater 27 and an injection valve 16 according to signals output from the temperature controller 42 and the PLC 43, and an operation displaying panel 45 which performs necessary displaying.
Since the constant-temperature liquid circulating apparatus 101 cools constant-temperature liquid whose temperature has been elevated in the load 2 by the heat exchanger 25 and heats the cooled constant-temperature liquid by the heater 27 to produce a constant-temperature liquid with a predetermined temperature, it is made easy to conduct a temperature adjustment of the constant-temperature liquid.
However, since the constant-temperature liquid circulating apparatus 101 heats the constant-temperature liquid which has been cooled in the heat exchanger 25 by the heater 27, the amount of power required for an operation is increased. In particular, according to the operation condition of the circulating apparatus 101, such a phenomenon that the compressor 7, the pump 28 and the heater 27 are made conductive simultaneously occurs, and it is necessary to increase the allowance amount of current conduction to the circulating apparatus 101 in order to respond to this phenomenon, and an equipment cost for current conduction is also increased.
As an apparatus which has solved such a problem, there is a constant-temperature liquid circulating apparatus shown in FIG. 4.
A constant-temperature liquid circulating apparatus 91 shown in FIG. 4 comprises a constant-temperature liquid circuit section 93 which cools constant-temperature liquidcirculating from a load 2 to a predetermined temperature to supply the same to the load 2, a refrigerating circuit section 92 for cooling the constant-temperature liquid, and a control section 94 for controlling the temperature of the constant-temperature liquid supplied to the load 2.
The refrigerating circuit section 92 comprises a main circuit section 50 provided with a compressor 7, a condenser 8, a first electronic expansion valve 56, an evaporator 10 and a piping connecting theses members in series; a pressure sensor 61 and a temperature sensor 62 provided in the main circuit section 50; a hot gas circuit section 58 provided with a second electronic expansion valve 59 which supplies a portion of refrigerant with a high temperature bypassing the condenser 8 and the first electronic expansion valve 56 to be discharged from the compressor 7 to the evaporator 10; and a circulating circuit 12 provided with an electronic expansion valve 57.
The constant-temperature liquid circuit section 93 comprises a tank 24 for constant-temperature liquid, an overflow tank 64 in the tank 24, a heat exchanger 25 which cools constant-temperature liquid circulated from the load 2 in the evaporator 10, a temperature sensor 37 which detects the temperature of constant-temperature liquid, a level switch 29, and a pump 28 which supplies constant-temperature liquid whose temperature has been adjusted to a predetermined temperature to the load 2 to circulate the same.
The control section 94 comprises a PLC 43, an electromagnetic contactor/electromagnetic switch 67, an operation display panel 45, and an expansion valve controller 96, and the expansion valve controller 96 controls the opening degrees of the electronic expansion valves 56, 57 and 59 individually to adjust constant-temperature liquid to a predetermined temperature by the signals from the temperature sensor 37, 62 and the pressure sensor 61.
Then, in the constant-temperature liquid circulating apparatus 91 shown in FIG. 4, since the opening degrees of the first and second electronic expansion valves 56, 59 are controlled by the control section 94 to control the refrigerating capacity of the refrigerating circuit section 92 so that the temperature of the constant-temperature liquid supplied to the load 2 can be controlled accurately, the heater 27 for preparing constant-temperature liquid with a predetermined temperature, which is provided in the constant-temperature liquid circulating apparatus 1 shown in FIG. 3 is made unnecessary.
However, since the constant-temperature liquid circulating apparatus 91 shown in FIG. 4 controls the refrigerating capacity of the refrigerating circuit section 92 by only controlling the opening degrees of the first and second electronic expansion valves 56, 59, a time required for reaching a target temperature is short, but it may not be said that controllability to disturbances (change in flow rate of constant-temperature liquid, change in external thermal load, change in temperature of cooling water in the condenser and the like) is good.
A ploblem to be solved by the invention is to provide a constant-temperature liquid circulating apparatus which is of an energy saving type, whose time required for reaching a target temperature is short, whose controllability to disturbance is excellent and whose size can be reduced.
In order to solve the above problem, a constant-temperature liquid circulating apparatus according to the present invention is a constant-temperature liquid circulating apparatus comprising a constant-temperature liquid circuit section which cooling or heating a constant-temperature liquid returned back from a load to a predetermined temperature to supply the same to the load, a refrigerating circuit section for cooling or heating the constant-temperature liquid, and a control section, wherein the refrigerating circuit section comprises a main circuit section which is provided with a compressor whose revolution speed is controlled by an inverter power source, a condenser, a first electronic expansion valve, an evaporator and piping connecting the compressor, the condenser, the first electronic expansion valve and the evaporator in series, and a hot gas circuit portion which has a second electronic expansion valve which bypasses the condenser and the first electronic expansion valve to supply a portion of refrigerant with a high temperature discharged from the compressor to the evaporator; the constant-temperature liquid circuit section comprises a tank for constant-temperature liquid, a heat exchanger which cools or heats the constant-temperature liquid circulating from the load in the evaporator, at least one temperature sensor which detects the temperature of a constant-temperature liquid, and circulating means which supplies a constant-temperature liquid whose temperature has been adjusted to a predetermined temperature to the load to circulate the same; and the control section controls the opening degrees of the first and second electronic expansion valves and the revolution speed of the compressor according to a signal from the temperature sensor to control the temperature of the constant-temperature liquid supplied to the load.
In the constant-temperature liquid circulating apparatus, it is suitable that the refrigerating circuit section has at least one temperature sensor or pressure sensor which detects the temperature or pressure of the refrigerant; and the control section controls the opening degree of the first electronic expansion valve according to a signal from the temperature sensor or pressure sensor in the refrigerating circuit section instead of the signal from the constant-temperature liquid temperature sensor or together with the signal from the constant-temperature liquid temperature sensor, and it is preferable that the temperature sensors or the pressure sensors in the refrigerating circuit section are respectively provided at an inflow side and an outflow side of the evaporator of the main circuit portion; and the control section controls the opening degree of the first electronic expansion valve according to a deviation signal based upon a signal from the temperature sensors or pressure sensors provided at the inflow side and the outflow side of the evaporator and controls the opening degree of the second electronic expansion valve according to a signal from the constant-temperature liquid temperature sensor.
A constant-temperature liquid circulating apparatus according to the present invention is a constant-temperature liquid circulating apparatus comprising a constant-temperature liquid circuit section which cooling or heating a constant-temperature liquid returned back from a load to a predetermined temperature to supply the same to the load, a refrigerating circuit section for cooling or heating the constant-temperature liquid, and a control section, wherein the refrigerating circuit section comprises a main circuit section which is provided with a compressor whose revolution speed is controlled by an inverter power source, a condenser, a first electronic expansion valve, an evaporator and piping connecting the compressor, the condenser, the first electronic expansion valve and the evaporator in series, and a hot gas circuit portion which has a second electronic expansion valve which bypasses the condenser and the first electronic expansion valve to supply a portion of refrigerant with a high temperature discharged from the compressor to the evaporator; the constant-temperature liquid circuit section comprises a tank for constant-temperature liquid, a heat exchanger which cools or heats the constant-temperature liquid returned back from the load in the evaporator, at least one temperature sensor which detects the temperature of a constant-temperature liquid, and circulating means which supplies a constant-temperature liquid whose temperature has been adjusted to a predetermined temperature to the load to circulate the same; and the control section controls the opening degrees of the first and second electronic expansion valves and the revolution speed of the compressor according to a signal from the temperature sensor to control the temperature of the constant-temperature liquid supplied to the load to a predetermined temperature, so that the refrigerating capacity of the refrigerating circuit section is controlled by controlling the revolution speed of the compressor in addition to controlling effected by the first and second electronic expansion valves.
That is, since the control section controls the revolution speed of the compressor to control the temperature or the pressure of hot gas by controlling the frequency of an inverter power source of the compressor and the hot gas is supplied to the evaporator while the hot gas is associated with the control of the first and second expansion valves, the refrigerating capacity of the refrigerating circuit section can be controlled.
Accordingly, since the constant-temperature liquid circulating apparatus according to the present invention controls the refrigerating capacity of the refrigerating circuit section not only by controlling effected by the first and second electronic expansion valves but also by controlling the revolution speed of the compressor, the constant-temperature liquid supplied to the load can accurately be controlled to a predetermined temperature and a time required for reaching the target temperature is considerably made fast, and controllability to disturbance is excellent.
Also, since, even if a small-sized compressor is used, the compressor can achieve the same refrigerant circulating amount as that of the conventional apparatus by operating the compressor at a high frequency, the apparatus can be small-sized, and since the revolution speed can be reduced by operating the compressor at a low frequency when the refrigerant circulating amount may be small, noises generated by the compressor can be suppressed and consumption power can be reduced.
Also, the constant-temperature liquid circulating apparatus according to the present invention does not require a heater for heating constant-temperature liquid, because the temperature of constant-temperature liquid to be supplied to a load can be controlled to a predetermined temperature accurately.
Accordingly, the constant-temperature liquid circulating apparatus according to the present invention can achieve energy saving and can be manufactured to a small-sized one.